I don't know what was ___ on the playgroundA.happen B happened C _英语解答

I don't know what was ___ on the playground
A.happen B happened C chappens D happening

人气：147 ℃　时间：2020-03-29 22:46:46

解答

B happened
我不知道操场上(刚才)发生了什么事
要被动语态,因为是什么被发生了,如果D的话,你不能有 was.
be+V 过去分词为被动语态!